That assumption is not quite right. Self builds do happen in London, they happen regularly, and for the right person on the right site they can produce an extraordinary result. But the challenges are real and different from what you face building elsewhere. Land is expensive and hard to find, planning is tougher, sites are constrained, and managing a build while living in one of the world’s most expensive cities adds financial pressure that does not exist in the same way when you are building on a rural plot.

This guide covers what self build in London actually involves, the different routes available, how to find a plot, how to finance it, what it is likely to cost, and the questions you need to answer honestly before committing. If you want to understand what building new involves more broadly, our guide to planning permission in London is a good place to start.

What Does Self Build Actually Mean?

Self build does not mean you physically lay every brick yourself. In practice, most self builders commission professionals to design and build their home. What makes it self build is that you are the client and decision maker throughout, rather than buying a finished home from a developer.

There are three routes that fall under the self build umbrella, and it is worth understanding the difference between them.

Full self build

You source the land, commission the design, manage the planning process, appoint the contractor, and oversee the build. You are the client in every sense. You carry all the decisions and all the risk. In return you get complete control over what gets built and potentially better value than buying a finished equivalent from a developer.

Custom build

You buy a serviced plot from a developer or enabling body that has already obtained planning permission and put infrastructure in place. You then design and build your home within the parameters set out by the planning consent. Custom build reduces the risk and complexity compared to full self build because the hard work of finding and consenting the land has already been done. In London, custom build plots are rare but not non-existent.

Managed self build

You appoint a project manager or contractor who takes on most of the day-to-day management of the build on your behalf. You retain ownership of the process and the decisions but you are not spending your weekends chasing subcontractors. For most London self builders with demanding jobs and limited construction experience, this is the most realistic route.

Most people who say they want to self build actually mean managed self build. That is not a lesser version of the idea. It is a practical approach that produces excellent results without requiring you to become a part-time construction manager.

Is Self Build Viable in London?

Yes, but with an honest set of caveats.

Land cost is the biggest barrier

London land prices are high, and a plot with planning permission commands a significant premium. A typical inner or mid London plot for a single dwelling will cost anywhere from £300,000 to £700,000 or more depending on location and what planning has already been secured. Add construction costs of £2,500 to £4,000 per square metre and professional fees on top, and the total project cost for a four-bedroom house in London can easily exceed £900,000 to £1,200,000. Our guide to finding and buying a building plot in London covers the plot search in detail.

The financial equation still works for many self builders. Comparable finished homes in London often cost more than the total project cost of building. The gap varies by location and specification, but a well-managed London self build can produce a home worth meaningfully more than it cost to build, which is one of the primary motivations.

Financing is more complex than a standard mortgage

You cannot buy a plot with a standard residential mortgage. Self build finance is a specialist product, released in stages tied to construction milestones rather than as a lump sum at completion. Most lenders require a deposit of 25% of total project costs and carry higher interest rates than standard mortgages, typically 1 to 2 percentage points above equivalent residential rates.

The cash flow implications are significant. Even with an advance-stage mortgage, you will need enough capital to fund each stage of the build before the next tranche is released. In London, where construction costs are high, those stage payments can be substantial.

Planning takes time and is not guaranteed

Every new dwelling in London requires full planning permission. You cannot assume that owning a plot means you will get permission to build on it. The design needs to pass the council’s scrutiny on character, scale, neighbour amenity, and increasingly on energy performance. In conservation areas the bar is higher. On constrained sites the constraints are real. Budget time and money for the planning process before a brick is laid.

The Self Build Register: Your First Step

Every London borough is legally required to maintain a Right to Build register. This is a list of people who want to self-build in the borough. Councils are required by law to bring forward enough serviced plots to meet the demand recorded on the register within a rolling three-year period. Registration costs nothing, takes a few minutes, and creates a legal obligation on the council. Register in every borough you would consider building in through righttobuildportal.org.uk.

The register does not guarantee you a plot. In London, where land is scarce and councils vary significantly in how seriously they take the obligation, it is not a fast route to a site. But it signals your intent, keeps you on the council’s radar, and in some cases has been used as supporting evidence in planning appeals and Local Plan representations to argue that more self-build plots should be identified.

Finding a Plot in London

This is the hardest part of self building in London and the part that takes the most time. Most plots never reach the open market. The best way to find one is to be active rather than passive.

• Register on dedicated plot-finding sites: Plotfinder.net and PlotBrowser.com aggregate what is openly listed. Set up alerts for your target boroughs and check them regularly.
• Talk to land agents in your target area. The relationship matters more than the portal. Agents tip off buyers they know before anything goes online.
• Search planning portals for recently approved new dwellings and look at adjacent sites. Where one has been approved, another nearby may be viable.
• Walk your target streets. Gaps between buildings, unused garages, overgrown corners and neglected plots are all worth investigating. Ownership searches on Land Registry cost £3 per title.
• Tell your architect, structural engineer, and any professionals you are already working with that you are looking. Construction professionals know about sites before they are listed.

The people who find plots fastest in London are the ones who are most visible and most active. Passive searching on portals alone can take years. Active networking, direct approaches to landowners, and relationships with agents and professionals produces results significantly faster.

How to Finance a Self Build in London

Self build finance works differently from a standard residential mortgage. Understanding the structure before you start is essential because cash flow is one of the most common causes of self build projects running into difficulty.

Self build mortgages

A self build mortgage releases funds in stages rather than as a lump sum. There are two payment structures.

Most lenders require a minimum deposit of 25% of total project costs, covering both land and construction. Borrowing is typically capped at 75% of total project cost or 70 to 75% of the final completed value, whichever is lower. Interest rates are typically 1 to 2 percentage points above equivalent residential rates.

The Help to Build equity loan scheme, which allowed self builders to borrow with a 5% deposit supported by a government equity loan of up to 40% in London, closed to new applications on 31 March 2025. It is no longer available. For current self build mortgage products, a specialist broker such as Buildstore is the most efficient route to market.

Bridging finance

Faster to arrange than a self build mortgage but significantly more expensive. Bridging is useful if you need to move quickly on a plot, if the plot has no planning permission yet, or if a self build mortgage does not cover the full project cost. Expect rates of 0.75% to 1.5% per month. Use bridging for short gaps rather than as the primary funding vehicle for a two-year build.

Equity release from an existing property

If you own a home with significant equity, remortgaging to release capital for a self build is a common approach. You carry two sets of borrowing costs simultaneously during the build, which is a real financial pressure in London where living costs are high, but it avoids the complexity of a specialist self build mortgage product.

What Does a Self Build Cost in London?

Construction costs for a self build in London sit within the same range as any new build: roughly £2,500 to £4,000 per square metre depending on specification and site complexity. The difference is that as a self builder you have more control over the specification and more opportunity to make choices that push costs in either direction.

One significant financial advantage of self build: VAT on new build construction is zero-rated at 0%. If you are buying materials directly, you pay 20% VAT at the point of purchase and reclaim it after completion through the HMRC DIY Housebuilder Scheme. Materials bought and installed by your main contractor are zero-rated at source. Either way, you save 20% on construction labour and materials compared to renovation. Our guide to VAT on a new build covers this in full.

Community Infrastructure Levy: The Self Build Exemption

Community Infrastructure Levy (CIL) is a charge applied by many London boroughs to new residential development. On a three-bedroom house in an inner London borough, CIL can run to tens of thousands of pounds. Self builders building a home for their own occupation are exempt from CIL. But the exemption is not automatic: you must apply for it before work starts. If you begin work without claiming the exemption, you lose it. The process involves submitting Form 7 Part 1 (claiming the exemption before work starts) and Form 7 Part 2 (confirming owner occupation after completion). Check your borough’s CIL charging schedule and exemption process on the Planning Portal before you break ground.

The CIL self build exemption must be claimed before work starts. There is no retrospective application. Missing this step on a project in a high-CIL borough can mean a five-figure charge that could have been avoided entirely.

Biodiversity Net Gain: The 2026 Change Self Builders Need to Know

From 6 August 2026, the specific exemption that previously applied to self build and custom build projects from mandatory Biodiversity Net Gain has been removed. For planning applications submitted on or after that date, self builds are subject to the same 10% BNG requirement as any other new residential development.

In practice this means your planning application needs to include a biodiversity baseline assessment and a BNG calculation demonstrating that the development achieves at least a 10% gain over pre-development levels. On a small urban plot this can usually be achieved through careful landscaping and planting choices. But it needs to be in the design from the start, not addressed as an afterthought.

Honest Realities: What Self Build in London Demands of You

Self build is presented as a dream in most of the media coverage it gets. The reality is that it demands a significant amount of time, decision-making capacity, financial resilience, and stress tolerance. In London, those demands are amplified.

• You will make hundreds of decisions during the project. Some of them will be wrong. Budget for that.
• The programme will almost certainly take longer than you expect. Two to four years from finding a plot to moving in is typical for a London self build.
• Living costs in London during a long build are a real financial burden, especially if you are renting while your capital is tied up in the project.
• Managing professionals, contractors, and the planning process alongside a full-time job is genuinely hard. Most self builders either take time away from work during key phases or appoint a project manager to carry the day-to-day load.
• The result, when it works, is a home that is exactly what you wanted, built to a standard you controlled, in a location you chose. For the people who get through it, the answer to whether it was worth it is almost always yes.

Thinking About a Self Build in London?

We work with self builders across all 33 London boroughs, from people who have already found their plot to people still working out whether the numbers stack up. If you want a straight conversation about what your project is likely to involve, what it will cost, and what the realistic timeline looks like, get in touch.

DEVELOPER NOTES

Internal links: /blog/planning-permission-london-guide, /blog/how-to-find-and-buy-a-building-plot-in-london, /blog/do-you-pay-vat-on-a-new-build-london, /contact

External links: righttobuildportal.org.uk, Plotfinder.net, PlotBrowser.com, Buildstore finance (buildstore.co.uk/finance), Planning Portal (planningportal.co.uk)

Suggested meta description: Self build in London is harder than elsewhere but it happens regularly. This guide covers the routes available, how to find a plot, self build mortgages, what it costs in 2026, and the honest realities of building in the capital.

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Frequently Asked Questions

Is self build possible in London?

Yes. It happens across all 33 London boroughs. The challenges are real: land is expensive and hard to find, planning is more demanding than in most parts of the country, and construction costs carry a London premium. But the same factors that make London hard to self build in also mean that a successfully completed project can produce a home worth significantly more than it cost to build. For the right person on the right site, it is absolutely viable.

How do I find a self build plot in London?

Most London plots never reach the open market. The most effective approaches are: registering on the Right to Build register for your target boroughs, using dedicated plot-finding sites with alerts set up, building relationships with land agents who specialise in residential development land, searching planning portals for recently approved new dwellings and looking at adjacent sites, and walking your target areas to identify unused land. Our guide to finding and buying a building plot in London covers all of these routes in detail.

How is a self build mortgage different from a standard mortgage?

A self build mortgage releases funds in stages tied to construction milestones rather than as a lump sum at completion. Deposits are typically 25% of total project costs. Interest rates are usually 1 to 2 percentage points higher than equivalent residential rates. You can choose between arrears payments, where you fund each stage then get reimbursed, or advance payments, where funds are released before each stage starts. Once the build is complete, the mortgage usually converts to a standard residential product.

Do self builds pay VAT?

New build construction is zero-rated for VAT, which means your main contractor does not charge you 20% on their labour and materials. If you are buying materials directly, you pay 20% VAT at the point of purchase and reclaim it after completion through HMRC’s DIY Housebuilder Scheme. Professional fees (architect, engineer, surveyor) are always charged at 20% VAT and cannot be reclaimed. Our guide to VAT on a new build explains the full process.

Do I need to pay Community Infrastructure Levy on a self build?

Self builders building for their own occupation are exempt from CIL, which can be a significant saving in boroughs with high charging schedules. But the exemption must be claimed before work starts by submitting Form 7 Part 1 to the council. Starting work without claiming the exemption means you lose it permanently. Check your borough’s CIL charging schedule and confirm the process before any groundworks begin.

Does the Biodiversity Net Gain requirement apply to self builds?

From 6 August 2026, yes. The specific exemption that previously applied to self build and custom build projects was removed for planning applications submitted on or after that date. Your application now needs to demonstrate a minimum 10% biodiversity net gain over pre-development baseline, the same as any other new residential development. For a small urban plot this is usually achievable through thoughtful landscaping. Your ecologist and architect should address it during the design phase.

How long does a self build in London take?

Two to four years from finding a plot to moving in is the realistic range for a London self build. That includes the time to find and buy the plot, commission the design, obtain planning permission, carry out pre-construction surveys, put the build contract in place, and complete the construction. Simpler projects on straightforward sites with smooth planning can come in at the lower end of that range. Complex designs, difficult planning environments, or ground conditions that require investigation and specialist foundations can push significantly beyond it.

The post Can You Self Build in London? What You Need to Know appeared first on New Build Contractors..

Get the process wrong and you risk legal action, injunctions stopping work on site, and a programme that slips by months. Get it right and it runs quietly alongside your build without causing a problem.

This guide explains what the Party Wall etc. Act 1996 actually covers, which types of work trigger it, how the notice and award process works from start to finish, what it costs in London in 2026, and the mistakes that add time and money to a project. If you are at the planning stage of a new build, our guide to surveys needed before a new build covers the full pre-construction picture.

What Is the Party Wall Act?

The Party Wall etc. Act 1996 is the law that governs construction work affecting shared walls, boundary structures, and excavation near neighbouring buildings in England and Wales. It has been in force since 1997 and has not changed in 2026. What changes year on year is surveyor fees, notice volumes, and how individual boroughs handle related planning processes.

The Act gives building owners the right to carry out certain types of work that would otherwise require their neighbour’s permission or involve trespass. In return, it requires formal notice, sets out a process for resolving disputes, and protects adjoining owners from damage caused by the work.

One thing that trips people up immediately: there is no document actually called a party wall agreement. When people use that phrase, they mean one of two things. Either the neighbour has given written consent to the notice, which is the simplest outcome. Or surveyors have been appointed and have produced a Party Wall Award, which is a legally binding document setting out how the work will be carried out and what compensation applies if damage occurs. The Award is what most people are referring to when they say party wall agreement.

The Party Wall Act is entirely separate from planning permission. Even if your project has permitted development rights and does not need a planning application, you may still need to follow the Party Wall Act. The two processes run independently and have different triggers.

What Triggers the Party Wall Act?

The Act is triggered by three distinct types of work, each covered by a different section and requiring a different notice.

Work on an existing party wall or structure (Section 2)

This is the most commonly triggered section. It covers work directly to a shared wall or structure, including:

• Cutting into a party wall to insert beams or steels, for example in a loft conversion or rear extension.
• Raising or lowering a party wall.
• Underpinning a party wall.
• Demolishing and rebuilding a party wall.
• Removing a chimney breast built into a party wall.
• Weatherproofing a party wall where the adjacent property has been demolished.

A Party Structure Notice must be served at least two months before this type of work starts. This is the longest notice period under the Act and it sits directly on your construction programme. If you serve notice the week before your contractor is due to start, you are already two months behind.

Building a new wall at or on the boundary (Section 1)

This applies when you want to build a new wall on or astride the boundary line between your property and your neighbour’s. On a new build in London, this is common: rear extension walls, side return walls, and boundary walls are frequently built on or right up to the boundary.

A Line of Junction Notice must be served at least one month before this work starts. If the neighbour consents, the wall can be built astride the boundary as a shared party wall. If they do not consent, you can only build the wall entirely on your own land, which may affect the usable footprint of your building.

Excavation near a neighbouring building (Section 6)

This is the one that surprises people most. The Act is triggered by excavation within three metres of a neighbouring building if the excavation goes deeper than the neighbour’s foundations, or within six metres if a 45-degree line drawn downward from the base of the neighbour’s foundations would intersect the bottom of the excavation.

In London, where houses sit close together and many foundations are shallow Victorian or Edwardian footings, this section is triggered by a very high proportion of new build groundworks. Basement excavation almost always triggers it. Deep new build foundations on clay often trigger it. Even foundation work on an apparently separate new build plot can trigger it if the neighbouring property’s foundations are shallow enough.

A Notice of Adjacent Excavation must be served at least one month before this work starts, accompanied by plans showing the depth and position of the excavation.

Who Do You Need to Serve Notice On?

You must serve notice on every adjoining owner affected by the relevant work. This sounds straightforward but in London it often involves more people than expected.

• For a terrace or semi-detached house, this means both immediate neighbours on either side if the work affects both party walls.
• For a leasehold property, you need to serve notice on both the freeholder and any leaseholder whose lease has more than one year remaining. Missing either one makes the notice defective for that party.
• For excavation work, you may need to serve notice on neighbours who are not directly adjacent to your boundary but whose foundations fall within the three-metre or six-metre zones.
• For basement work in a terraced street, it is not uncommon to serve notice on three or four neighbouring properties.

Identifying all the relevant owners requires Land Registry searches. These cost £3 per title and are done online through HM Land Registry. Do not skip this step. Serving notice on the wrong person, or missing someone entirely, does not make the process go away. It just means the notice is invalid for the parties you missed, and you may need to start again.

What Happens After You Serve Notice?

Once a valid notice is served, the adjoining owner has 14 days to respond. There are three possible outcomes.

Consent

The neighbour agrees to the works in writing. This is the simplest and cheapest outcome. No surveyors need to be appointed, no Award needs to be prepared. You can proceed with the work as described in the notice once the notice period has expired. Keep the written consent safely: you may need it later.

Dissent

The neighbour disagrees or has concerns. This triggers the surveyor appointment process. Either an Agreed Surveyor is appointed to act for both parties, or each party appoints their own surveyor. The surveyors then prepare a Party Wall Award, which is a legal document setting out the method and sequence of the notifiable work, the surveyor’s access rights to inspect, and any compensation provisions if damage occurs.

No response

If the neighbour does not respond within 14 days, they are deemed to have dissented. This triggers the surveyor appointment process exactly as if they had formally dissented. Silence is not consent.

In London, dissent rates are higher than in most other parts of the country. Dense urban housing, close relationships between properties, and more litigious neighbours mean you should budget for the surveyor route as the likely outcome, particularly on basement and new build projects where the scope of work is significant.

Agreed Surveyor vs Two Surveyors: What Is the Difference?

When a neighbour dissents, the parties can choose between two approaches to appointing surveyors.

Agreed Surveyor

Both parties appoint one surveyor to act for them jointly. This is cheaper and faster. A single surveyor prepares the Award without the need for negotiation between two separate professionals. The total cost for this route in London in 2026 typically runs from £1,500 to £2,800 per neighbouring property.

The downside is that the Agreed Surveyor must be genuinely independent and acceptable to both parties. If the neighbour does not trust your suggested surveyor, or if a dispute arises during the works, the Agreed Surveyor route can break down.

Two surveyors

Each party appoints their own surveyor. The building owner pays both fees. The two surveyors negotiate the terms of the Award between them. If they cannot agree, they appoint a Third Surveyor to make the final decision on the disputed point.

This route is more expensive. In London in 2026, typical surveyor fees run from £750 to £1,800 per surveyor per neighbouring property. On a new build with two affected neighbours, each dissenting and each appointing their own surveyor, the party wall costs could run to £6,000 or more before any Third Surveyor is involved.

What Does a Party Wall Award Contain?

A Party Wall Award is a formal legal document. It typically includes:

• A description of the proposed works covered by the Award.
• The method and sequence of the notifiable work, including any specific requirements for how work is carried out near the party structure.
• A schedule of condition: a record of the state of the neighbouring property before work starts, including photographs. This is the baseline for any future claims about damage caused by the works.
• Rights of access for the surveyors to inspect the works during construction.
• Security for expenses if required: in some cases, particularly for basement works, the Award may require the building owner to post a financial bond against potential damage.
• Compensation provisions: the process for assessing and paying compensation if the neighbouring property is damaged.

The schedule of condition is one of the most practically important parts of the Award. Without it, any claim by the neighbour that the works caused damage to their property becomes a dispute about what condition it was in before you started. With it, you have an agreed baseline that protects both parties.

What Does It Cost and Who Pays?

The building owner, meaning you as the person carrying out the works, pays all party wall costs. This includes your own surveyor’s fees, your neighbour’s surveyor’s fees, and any Third Surveyor fees if a dispute arises. This is a fixed rule under the Act and it applies regardless of whether your neighbour’s position is reasonable.

These are surveyor fees only. They do not include any compensation payments if damage is caused, or the cost of making good any damage to the neighbouring property during the works. Budget for party wall costs as a separate line item from your construction budget and do not assume neighbours will consent.

Common Mistakes That Cost Time and Money

Serving notice too late

The two-month notice period for Party Structure Notices sits directly on your construction programme. If your contractor is ready to start in eight weeks and you have not served notice yet, you are already behind. Serve notice as soon as your design is sufficiently developed to describe the works, not when you are about to start on site.

Serving an invalid notice

A notice that does not include all the required information, does not describe the works clearly, or is not served on all the relevant owners is invalid. An invalid notice does not start the clock. You may need to serve again from scratch. Common errors include missing leaseholders, describing the works too vaguely, and not including the required plans with an excavation notice.

Assuming silence means consent

It does not. If a neighbour does not respond within 14 days they are deemed to have dissented, which triggers the surveyor appointment process. Do not start work assuming your neighbour is happy because they have not said anything.

Starting work before the Award is in place

Starting notifiable work before a valid Award has been prepared is a breach of the Act. The neighbour can apply to court for an injunction to stop the works. In London, where party wall disputes are more common than elsewhere, this happens. An injunction stopping work on a new build site while surveyors are appointed and an Award is prepared can add weeks or months to the programme.

Starting work without following the Party Wall Act is not a minor administrative oversight. It gives the adjoining owner the right to go to court for an injunction. An injunction on a new build site means no work, the clock ticks, your contractor keeps charging preliminaries, and the damage to your programme and budget can be severe.

Not getting a schedule of condition

If no schedule of condition is prepared before work starts and the neighbour later claims damage, you have no agreed baseline to argue from. Always ensure the Award includes a thorough schedule of condition with photographs, even if the neighbour appears relaxed about the works.

Building in London and Need Help with Party Wall Notices?

We manage the party wall process as a standard part of every new build project we take on. That means notices go out at the right time, the process runs alongside the construction programme rather than holding it up, and you are not left chasing surveyors when your contractor is ready to start. Get in touch to talk through your project.

DEVELOPER NOTES

Internal links: /blog/what-surveys-do-you-need-before-a-new-build, /contact

External links: gov.uk Party Wall Act guidance (gov.uk), HM Land Registry title search (gov.uk)

Suggested meta description: The Party Wall Act triggers on more London projects than most homeowners expect. Here is what it covers, the three notice types, how the award process works, what it costs in 2026, and the mistakes that add time to a build.

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Developer note: a simple diagram showing the 3m and 6m excavation zones alongside the boundary line would significantly improve this post. Worth commissioning from a designer.

Frequently Asked Questions

Do I need a party wall agreement for a new build?

Almost certainly yes for at least one element of the work. A new build involves foundation excavation, which triggers the Act if the dig goes deeper than a neighbouring building’s foundations within three or six metres of that building. It also involves building new walls at or near the boundary, which triggers the Line of Junction Notice requirement. On a typical London new build plot, multiple notice types will apply across different phases of the groundworks and structure.

Can my neighbour stop my new build with the Party Wall Act?

No. The Party Wall Act does not give neighbours the right to stop your work. What it gives them is the right to have the work carried out in a way that protects their property, and the right to compensation if damage occurs. A neighbour who dissents triggers the surveyor appointment process, which produces a Party Wall Award setting out how the work proceeds. They cannot use the Act to prevent the work from happening at all.

What happens if I start work without serving party wall notice?

You are in breach of the Act. The neighbouring owner can apply to a court for an injunction to stop the work. Courts in England and Wales take this seriously and injunctions are granted. Once an injunction is in place, work stops until the party wall process is completed and an Award is in place. On a construction site with a contractor mobilised, a programme delayed by a court injunction is expensive. The costs of getting this wrong significantly exceed the costs of getting it right from the start.

Who pays for the party wall surveyor?

The building owner, meaning the person carrying out the works, pays all party wall costs. This includes both their own surveyor’s fees and the adjoining owner’s surveyor’s fees. It is a fixed rule under the Act. The only exception is if the neighbouring owner has requested work that benefits only them, in which case they contribute to those specific costs. For all standard party wall scenarios on a new build, you pay everything.

How long does the party wall process take?

If the neighbour consents in writing, the process is complete once the notice period expires, typically two months from the date of a Party Structure Notice or one month for a Line of Junction or Excavation Notice. If surveyors are appointed, the process from notice to completed Award typically takes six to ten weeks, though complex basement or new build cases can take longer, particularly in London where surveyor availability has been stretched through 2025 and 2026 as more homeowners extend rather than move.

Does the Party Wall Act apply to permitted development?

Yes. Planning permission status and party wall obligations are entirely separate. If your project is permitted development and does not need a planning application, you may still need to follow the Party Wall Act if the work meets any of the three triggers. The two processes are independent of each other and both need to be managed correctly.

Can I use the same surveyor as my neighbour?

Yes, this is the Agreed Surveyor route and it is often the most cost-effective option. One surveyor acts for both parties and prepares the Award independently. It requires both parties to agree on the same individual, and it works best when the relationship between neighbours is reasonably straightforward and the scope of work is not highly contentious. On complex projects or where the neighbour has strong concerns about the works, two separate surveyors may be more appropriate.

The post Party Wall Agreements Explained for London Homeowners appeared first on New Build Contractors..

Most people building or buying a new home know they need a structural warranty because their mortgage lender requires it. Far fewer actually understand what it covers, what it does not cover, how the claim process works, or what happens if they try to sell a home that does not have one.

This guide explains how structural warranties work in plain terms. It covers what is included, the difference between the defects period and the insurance period, which providers are worth knowing about, how much it costs, and what your options are if you are self-building. If you are concerned about what happens if your builder goes bust, our guide on contractor insolvency covers how a warranty fits into that picture.

What Is a Structural Warranty?

A structural warranty is a 10-year insurance-backed policy that protects a new home against significant defects in its design, materials, or workmanship. It is taken out by the builder or developer before or during construction, but it protects the homeowner, not the builder.

The policy stays with the property, not with the original buyer. If the home is sold within the 10-year term, the remaining cover transfers automatically to the new owner. This is one of the reasons mortgage lenders and conveyancing solicitors insist on it: it protects whoever owns the property, not just the person who commissioned the build.

You will hear these policies described by several different names: structural warranty, building warranty, new build warranty, latent defects insurance, inherent defects insurance. They all refer to the same thing. The name varies by provider and context but the purpose is the same.

How the Two-Period Structure Works

Every structural warranty is split into two distinct periods that work differently. Understanding this split is essential because the cover you have in years one and two is meaningfully different from the cover you have in years three to ten.

Years 1 and 2: the builder’s defects period

In the first two years after practical completion, the builder is responsible for fixing defects. If a window does not seal properly, a door frame is out of square, plaster cracks appear, or the heating system does not work as it should, you report it to the builder and they are obliged to put it right.

The warranty provider does not pay for repairs in this period. Their role is to act as a backstop if the builder disputes your claim, drags their feet, or goes out of business. Most providers have a resolution service that you can escalate to if you and your builder cannot agree. If the builder is insolvent, the warranty provider steps in directly.

Most defects in a new build show up in the first two years. This is the period when the building settles, materials dry out, and any workmanship problems become visible. Report every defect in writing during this period and keep records of what was reported and when.

Years 3 to 10: the structural insurance period

From year three onwards, the builder’s obligation ends and the insurance policy takes over. But the cover changes significantly. You can no longer claim for general defects or workmanship problems. The policy now only covers major structural issues: damage to load-bearing elements caused by a failure to build to the warranty provider’s technical standards.

What counts as structural varies slightly between providers but typically includes foundation failure, structural movement affecting load-bearing walls or roofs, major roof structure failure, and external wall systems that fail to keep water out. What is explicitly excluded is just as important to understand.

People regularly assume their structural warranty covers things it does not. A crack in plaster in year four is not a structural defect. A roof tile blown off in a storm is not a structural defect. If you are unsure whether your problem is covered, read your policy carefully before you contact the provider, because how you frame the claim matters.

Why You Cannot Sell Without One

If you build a new home without a structural warranty and then try to sell it within the first 10 years, you will almost certainly find that buyers cannot get a mortgage on it. Most high street lenders require a recognised structural warranty as a condition of lending on a new build property. Without one, the pool of potential buyers shrinks to cash buyers only.

Even cash buyers will expect a significant discount to reflect the absence of warranty protection and the additional legal risk. And their solicitor will flag it during conveyancing regardless. The problem does not go away.

Some lenders will accept a Professional Consultant’s Certificate (PCC) as an alternative to a structural warranty. A PCC is a document signed by a suitably qualified professional who has supervised the construction and is willing to certify that it was built to an appropriate standard. PCCs are accepted by some lenders but not all, and acceptance depends on the qualifications of the signatory and the lender’s specific criteria. Check UK Finance’s lender handbook for what individual lenders accept.

Get the warranty in place before you start building, not after. Retrospective warranties are difficult to obtain and expensive. Some providers will not issue them at all once a build is complete without full inspection records from during the construction process.

Who Are the Main Warranty Providers?

There are around a dozen providers operating in the UK market. Here are the main ones you are likely to encounter and what distinguishes them.

NHBC is the name most buyers recognise and the one most solicitors and lenders are comfortable with. But it is not the only valid option, and for smaller or more complex projects the alternative providers can offer comparable cover, often more quickly and sometimes at lower cost.

For a self-build or bespoke new build in London, NHBC requires the builder to be a registered NHBC member, which not all contractors are. If your contractor is not NHBC-registered, one of the alternative providers is the practical route.

What Does a Structural Warranty Cost?

The warranty is paid for by the builder or developer as part of the cost of the project, not directly by the homeowner at the point of purchase. But the cost is factored into the overall build cost, so it is worth understanding what the figure looks like.

For the NHBC Buildmark warranty, the developer typically pays between £1,500 and £3,500 depending on the size and value of the property. Larger, higher-value homes attract higher premiums. Alternative providers are sometimes cheaper, particularly for smaller schemes or self-builds, but premiums vary based on the project type, the contractor’s track record, and the insurer’s assessment of risk.

Set against the total cost of a new build in London, a structural warranty premium is a relatively small line item. Set against the cost of a major structural remediation without insurance, it is exceptional value. Foundation remediation, for example, can run to six figures on a London property. The warranty premium is not optional on any sensible risk basis.

Self-Build Warranties: What Are Your Options?

If you are commissioning a bespoke new build or managing your own self-build, the warranty landscape is slightly different because you are not buying from a developer who already has a warranty in place. You need to arrange it yourself.

Register with a provider early

Most warranty providers need to register the project before construction starts. They will carry out technical inspections at key stages during the build, similar to building control but focused on the warranty provider’s own technical standards. You cannot usually obtain a structural warranty retrospectively on a completed build without full inspection records, which is why early registration matters.

Your contractor’s registration status matters

NHBC requires the contractor to be a registered member. If your chosen contractor is not NHBC-registered, you will need to use an alternative provider. This is not necessarily a problem, but it is something to establish before you appoint the contractor, not after work has started.

Self-build specific policies

Several providers offer policies specifically designed for self-builds and bespoke commissions, including LABC Warranty, Build-Zone, and Protek. These are structured slightly differently from developer warranties but provide equivalent protection. Your mortgage lender will need to confirm they accept the specific provider before you commit.

Professional Consultant’s Certificate as an alternative

Some self-builders use a PCC instead of a structural warranty, where a suitably qualified architect or surveyor has supervised the construction throughout. PCCs are cheaper to obtain than a full warranty but are accepted by fewer lenders. If you plan to sell or remortgage within the first 10 years, check with your intended lender before relying on a PCC rather than a full warranty.

How to Make a Claim

The process differs depending on which period you are in.

In years 1 and 2

Report defects to your builder in writing. Keep a record of every item reported, the date it was reported, and the response you received. Most warranty providers have an online portal or defect reporting form for this period. If the builder does not respond within a reasonable timeframe or disputes the claim, escalate to the warranty provider’s resolution service.

In years 3 to 10

Contact the warranty provider directly. They will assess whether the problem qualifies as a structural defect under the policy terms. Be specific about what has failed and how. Provide photographs and any reports from independent surveyors if you have them. If the claim is rejected and you believe it should not have been, you can escalate to the Financial Ombudsman Service.

Document everything from day one

The strongest warranty claims are supported by good records. Keep your warranty policy document, the original build specification, any correspondence with your builder about defects, and inspection reports from during the construction period. If you have had to pay for independent surveys or temporary repairs while waiting for a claim to be resolved, keep those receipts too.

Do not carry out permanent repairs to a suspected structural defect before the warranty provider has inspected it. If you fix the problem before the inspection, the provider may argue there is no longer evidence of the defect and decline the claim.

Building in London and Need Advice on Warranties?

We build across all 33 London boroughs and manage the warranty process as part of every project. If you want to understand which warranty is right for your build, what your mortgage lender will accept, or how the process works from registration to completion, get in touch with our team.

DEVELOPER NOTES

Internal links: /blog/what-happens-if-your-builder-goes-bust, /contact

External links: NHBC Buildmark (nhbc.co.uk), UK Finance lender handbook (ukfinance.org.uk)

Suggested meta description: A structural warranty is a 10-year insurance policy on your new build. Here is what it actually covers, what it does not, which providers to know, what it costs, and why you cannot sell without one.

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Frequently Asked Questions

Is a structural warranty a legal requirement?

No, it is not a statutory legal requirement in the same way that building regulations approval is. But it is effectively mandatory in practice because most mortgage lenders require a recognised structural warranty before they will lend on a new build property. Without one, your buyers will struggle to get a mortgage, which significantly limits who can purchase the property and at what price. If you are planning to sell or remortgage within 10 years, a structural warranty is not optional in any practical sense.

Does a structural warranty cover all defects?

No. In years one and two it covers defects reported to the builder, who is obliged to put them right. From year three onwards it covers major structural defects only: foundation failure, structural wall or frame failure, major roof structure failure, and external envelope failures causing damp penetration. It does not cover cosmetic issues, wear and tear, damage from your own alterations, appliances, landscaping, or problems caused by failure to maintain the property. Read the policy exclusions carefully before assuming something is covered.

What happens if my builder goes bust during the defects period?

If your builder becomes insolvent during years one and two, the warranty provider steps in to cover the cost of remedying defects that the builder can no longer fix. This is one of the most important protections a structural warranty provides. Before completion, most policies also provide insolvency cover for deposits paid, typically up to 10% of the purchase price or £100,000, whichever is lower. Our guide on what happens if your builder goes bust covers this in more detail.

Can I get a structural warranty after the build is complete?

It is very difficult and sometimes impossible to obtain a retrospective structural warranty on a completed build. Most providers require registration before construction starts and carry out inspections at key stages during the build. Without those inspection records, there is no basis for the insurer to assess the risk. If you are considering buying a new build property that does not have a warranty, get specialist advice from a solicitor before proceeding.

How long does a structural warranty last?

The standard term is 10 years from the date of practical completion. Some providers offer 12-year policies. The warranty transfers automatically to new owners when the property is sold, so if you buy a new build that is three years old, you inherit the remaining seven years of cover. There is no way to extend or renew a warranty once it expires.

Do I need a structural warranty if I am self-building?

Yes, for the same reasons that apply to any new build. If you plan to sell or remortgage within 10 years, your buyers or lender will require one. The process is slightly different for self-builds because you need to arrange it yourself before construction starts rather than it being provided by a developer. Several providers offer self-build specific policies including LABC Warranty, Build-Zone, and Protek. Your contractor’s NHBC registration status will determine whether NHBC Buildmark is available to you.

The post What Is a Structural Warranty and Do You Need One? appeared first on New Build Contractors..

Building regulations set the minimum legal standards for construction in England. They cover everything from how strong your foundations need to be, to how much heat your walls are allowed to lose, to where your smoke alarms go. If your build does not meet them, you cannot legally occupy the property. And if you try to sell it later without the right paperwork, you will run into serious problems.

The regulations have also changed significantly in the past few years. If you are planning a new build in London in 2026, you are building to a different set of energy standards than someone who built five years ago. This guide explains how building regulations work, what the main parts cover, how the process runs from start to finish, and what has changed recently. If you have not yet sorted planning permission, our guide to planning permission in London covers that process in full.

Planning Permission vs Building Regulations: What Is the Difference?

These two things get confused regularly, and it is worth being clear about the distinction from the start.

Planning permission controls whether you are allowed to build at all and what the building can look like from the outside. It is concerned with the impact of your development on the surrounding area: scale, appearance, neighbour amenity, and so on.

Building regulations control how the building is constructed. They are about safety, health, energy performance, and the technical standards of the build itself. They apply whether or not planning permission is required.

You can have planning permission without building regulations approval, and you can need building regulations approval for work that does not need planning permission. On a new build you will almost always need both, and they run as parallel processes managed by different people.

A common mistake is treating building regulations as something to deal with after planning. In practice, your architect and structural engineer should be designing to building regulations standards from day one. Retrofitting compliance at the end is expensive and sometimes impossible.

What Are the Approved Documents?

Building regulations in England are published as a series of Approved Documents, each covering a specific aspect of construction. You do not have to follow these documents to the letter; they are guidance rather than law. But if you depart from them, you need to demonstrate an alternative way of achieving compliance, which in practice means more work and more risk. Most builds follow the Approved Documents closely.

Here is what the main ones cover and why they matter for a new build:

Not every part will be relevant to every build, but for a new dwelling in London, most of them will come into play at some stage.

What Has Changed in 2025 and 2026?

This is the area that catches the most people out, particularly those who built or extended a property a few years ago and assume the rules are the same.

They are not.

Energy efficiency: Part L and the Future Homes Standard

The biggest change in recent years is to Part L, which governs energy efficiency. New homes built from 2025 onwards must produce approximately 75 to 80% less carbon dioxide than those built under the 2013 regulations. That is a significant jump.

In practice this means much better insulation throughout the building envelope, higher performance windows and doors, much tighter airtightness standards, and in most cases a low carbon heating system rather than a gas boiler. Air source heat pumps have become the standard heating solution for new builds in London, and the design of the home needs to accommodate them from the start rather than as an afterthought.

Solar panels are increasingly expected, and the Building Regulations etc. (Amendment) (England) Regulations 2026, published in March this year, introduced a new requirement for on-site renewable electricity generation when a new dwelling is constructed. This brings the Future Homes Standard into force in stages, with full implementation expected to come into effect from March 2027.

If you are at early design stage, make sure your architect and mechanical engineer are designing to the current Part L standards, not to what was required three or five years ago. The gap is large and catching up is costly.

Overheating: Part O

Part O was introduced in 2022 and is still relatively new in practice. It applies to all new residential buildings and requires designers to demonstrate that the home will not overheat in a warming climate.

This is more relevant than it sounds. A home built to today’s airtightness and insulation standards retains heat very effectively, which is great in winter and a significant problem in summer. Part O requires a combination of passive measures (limiting solar gain through glazing orientation and sizing) and active measures (opening windows, mechanical ventilation) to keep internal temperatures within acceptable limits.

In London, overheating is taken more seriously than in many other parts of the country. The urban heat island effect means city temperatures are already higher than surrounding areas, and south-facing glazed extensions or rooms with large roof lights can become genuinely uncomfortable without proper design.

Fire safety: Part B

Following the Grenfell Tower fire and the subsequent review of fire safety standards, Part B has been significantly strengthened for higher risk buildings. For new residential buildings over 18 metres in height, a requirement for second staircases comes into force in England on 30 September 2026. This was already a requirement of the Greater London Authority for tall residential buildings in London, so London developers have been working to this standard for some time. If your project is a taller residential development, check the current requirements carefully with your architect and the Building Safety Regulator.

For straightforward single-family new builds, Part B requires a working smoke alarm on every floor, heat alarms in kitchens, interconnected alarms throughout the property, fire doors where required, and clear means of escape from all habitable rooms.

Electric vehicle charging: Part S

All new residential buildings must now include infrastructure for electric vehicle charging. For a single new dwelling with associated parking, this means a dedicated EV charging point. Your electrical design needs to include this from the start, as it requires a dedicated circuit from the consumer unit to the parking space.

How Does the Building Control Process Work?

Building control is the system that checks your build actually complies with building regulations during construction. It runs from before work starts through to completion, and it ends with a completion certificate that you will need to keep safely for the life of the building.

Step 1: Submit a full plans application

For a new build, you will almost always submit a Full Plans application to building control before construction starts. This involves submitting detailed architectural drawings, structural calculations, energy assessments, and specifications for review and formal approval. You can submit to your local authority building control department, or to a private Approved Inspector. The Planning Portal has a list of registered Approved Inspectors if you want to explore the private route.

Private Approved Inspectors are often faster and more responsive than local authority building control, but both routes are legally valid. For most London new builds, the choice comes down to speed, service, and the relationship your contractor has with a particular body.

Step 2: Start on site and notify building control

Before work begins, you must notify building control. From that point, you are responsible for giving adequate notice at each key stage of the build so that inspections can take place. These typically include:

• Commencement of works
• Foundation excavations (before concrete is poured)
• Damp proof course installation
• Oversite concrete or ground floor construction
• Drains (before backfilling)
• Structural frame and roof
• Insulation installation
• Completion

The inspector visits at each notified stage and checks that the work meets the required standard before you cover it up and move on. If they find a problem, they will tell you what needs to be rectified before the next stage can be signed off.

24 to 48 hours notice is typically required before each inspection. Build this into your construction programme and make sure your site manager knows when each notification needs to go in.

Step 3: Final inspection and completion certificate

Once all the work is complete and the final inspection is passed, building control issues a completion certificate. This is one of the most important documents your build produces.

Without it, you cannot legally sell the property. Solicitors acting for buyers will require it. Mortgage lenders will ask for it. If you try to sell a property built without building regulations approval or without a completion certificate, you will face significant delays and legal complications that are expensive and stressful to resolve.

Keep this document securely, alongside your planning consent and any other approvals. If you ever need to sell, remortgage, or make an insurance claim, it will be asked for.

Energy Assessments and SAP Calculations

Every new dwelling in England requires a Standard Assessment Procedure (SAP) calculation to demonstrate compliance with Part L. This is a technical calculation carried out by an accredited energy assessor that models the energy performance of the home. It is used to produce the Energy Performance Certificate (EPC) that every new build must have before it can be occupied or marketed. You can find an accredited SAP assessor through Elmhurst Energy’s search tool.

The SAP calculation needs to be done at two stages. The first is a Design Stage SAP, submitted with your building regulations application to demonstrate that the proposed design will meet the energy targets. The second is an As Built SAP, carried out after construction is complete and reflecting any changes made during the build. The As Built SAP is what produces the final EPC.

In practice this means your architect, mechanical engineer, and SAP assessor need to be working together from the start of the design process. The insulation specification, window sizes and orientations, airtightness target, heating system, and renewable energy provisions all feed into the calculation and cannot be treated in isolation.

Anything Different About London Specifically?

Building regulations are national, so the Approved Documents apply the same way across England. But there are a few things that are particular to London that are worth knowing about.

The London Plan

The London Plan is the strategic planning document for Greater London, produced by the Mayor. It adds requirements on top of national planning policy in several areas that affect building design, most significantly around energy and sustainability. New developments in London are expected to achieve zero carbon on site or offset the remaining emissions through a contribution to the borough’s carbon offset fund. This goes further than national building regulations.

Biodiversity Net Gain

The London Plan also requires developments to achieve a measurable uplift in biodiversity. From April 2024, Biodiversity Net Gain became a mandatory requirement nationally for most planning permissions, requiring a minimum 10% uplift over the pre-development baseline. In London, the Mayor’s guidance pushes for more than the national minimum on larger sites. This affects how your site is designed and landscaped, and you will need an ecological baseline assessment to quantify the gain. Our guide to surveys needed before a new build covers ecological surveys in more detail.

The Building Safety Regulator

The Building Safety Regulator became an independent statutory body in January 2026. For most single-family new builds in London, its direct involvement is limited. But if your project involves a building over 18 metres or seven storeys, you are now working within a more tightly regulated regime that includes the Gateway system: formal checkpoints before you can start work and before you can occupy the building. If your project falls into this category, seek specialist advice from your architect and consult the Building Safety Regulator’s guidance directly.

Common Mistakes Homeowners Make with Building Regulations

These come up regularly in our experience working across London boroughs.

Leaving the energy assessment too late

Some clients treat the SAP calculation as an administrative task to be done near the end of the project. It is not. It is a design tool. If the energy performance of your proposed design is not modelled until late in the process, you may find that you need to make significant and expensive changes to achieve compliance.

Not notifying building control at the right stages

If work is covered up before a building control inspector has signed it off, you may be required to open it up again for inspection at your cost. This is particularly relevant for foundations, drains, and insulation. Make sure whoever is managing the site knows when each notification needs to go in.

Assuming the completion certificate will arrive automatically

It will not. You need to notify building control that the work is complete and request a final inspection. If you move in without doing this, the completion certificate may never be issued, which creates a problem when you come to sell. Chase it before your builder demobilises from site.

Not keeping the paperwork

Completion certificates, energy performance certificates, structural warranties, fire safety documents, and electrical installation certificates all need to be kept for the life of the building. Create a property file from day one and make sure everything goes into it. Future owners and mortgage lenders will need these documents.

Building a New Home in London?

We work across all 33 London boroughs and manage every stage of the build process, including building regulations compliance and building control sign-off. If you want a team that handles this properly so you are not left chasing paperwork at the end, talk to us about your project.

DEVELOPER NOTES

Internal links: /blog/planning-permission-london-guide, /blog/what-surveys-do-you-need-before-a-new-build, /contact

External links: gov.uk Approved Documents, Planning Portal building control, HSE Building Safety Regulator, London Plan (london.gov.uk), Elmhurst Energy SAP assessors

Suggested meta description: Building regulations for new builds in London explained clearly: what the approved documents cover, how building control works, what has changed in 2025 and 2026, and the mistakes to avoid.

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Consider adding a ‘Last updated: June 2026’ note near the top, as the regulatory context is evolving quickly

Frequently Asked Questions

Do I need building regulations approval for a new build in London?

Yes, without exception. Building regulations approval is a legal requirement for all new dwellings. There is no exemption for residential new builds. You must submit an application, have the work inspected at key stages, and receive a completion certificate before the property can legally be occupied.

How long does building regulations approval take?

A Full Plans application must receive a decision within five weeks, or eight weeks if you agree an extension with the building control body. In practice, this is the approval of your submitted drawings. Inspections during the build happen as you notify at each stage. The final completion certificate is issued after the final inspection, typically within a few weeks of the build finishing, provided everything is in order.

Can I use a private building control inspector instead of the council?

Yes. Approved Inspectors are private companies registered with the Construction Industry Council that can carry out building control functions instead of the local authority. They are often faster and more flexible than local authority building control, and the choice is yours. Both routes produce legally equivalent outcomes. A list of registered Approved Inspectors is available through the Planning Portal.

What happens if work does not comply with building regulations?

The local authority has enforcement powers and can require you to alter or remove non-compliant work at your own cost. If you have already moved in or sold the property, you can still face enforcement action. This is why it is important to use a competent contractor, notify building control at the right stages, and not cover up work before it has been inspected.

What is an Energy Performance Certificate and do I need one?

An EPC is a document that rates the energy efficiency of a property on a scale from A to G. All new dwellings must have a valid EPC before they can be sold or rented out. For a new build, the EPC is produced from the As Built SAP calculation. It is a legal requirement, not optional. Your SAP assessor produces it once the build is complete and the final calculations are confirmed.

Does building regulations approval expire?

A building regulations approval does not expire, but the standards it was approved under may become outdated if significant time passes before work starts. If you receive building regulations approval and do not start work for several years, it is worth checking with your building control body whether the approval still reflects current standards, particularly around energy efficiency, which has changed significantly in recent years.

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